1. Field of the Invention
The present invention relates to a substrate transport apparatus and, more particularly, to a substrate transport apparatus for stably transporting a substrate and sensing a receiving state of the substrate.
2. Description of Related Art
During cleaning, submerging, depositing, and etching processes, a substrate must be transported to the respective processing positions. It is achieved by a substrate transport apparatus. A substrate transport apparatus is a robotic and automated apparatus that operates with a predetermined program to transport a substrate to respective processing positions.
A typical substrate transport apparatus has a thin-plate hand on which a substrate is placed. Corbels are formed at the hand for preventing separation of a substrate while transporting the substrate. Since the substrate transport apparatus simply transports a substrate placed on the hand, the substrate slides on the hand when being transported at a high speed.
As a result, a substrate transport speed of a substrate transport apparatus must be enhanced for raising a productivity of a semiconductor manufacturing equipment. Nonetheless, corbels formed at a hand are incapable of preventing a substrate from sliding out of the hand in spite of inertial force caused by a high transport speed of the substrate transport apparatus. In a conventional substrate transport apparatus using a reflective optical sensor to check whether a substrate exists, the reflective optical sensor does not often sense a substrate according to a notch or flat-zone position of the substrate.
As previously stated, a conventional substrate transport apparatus is not capable of preventing a substrate from sliding out when transporting the substrate. Due to the sliding of the substrate, the apparatus is not capable of transporting a substrate at a high speed. This results in decrease of a productivity.